Sir Terry Pratchett is one of Britain's best-selling authors. His science-fiction series Discworld has sold millions of copies worldwide. Pratchett is incredibly prolific — since his first novel was published in 1971, he has written on average two books every year.

But in 2007, 59-year-old Pratchett announced that he had been diagnosed with early-onset Alzheimer's disease. As a result, Pratchett can no longer read.

"When you read, I'm sure you don't realize that your eyes are going backwards and forwards and to this place and that place. Mine don't do that," he says.

Yet he continues to write, using dictation software. His latest book, The Carpet People, was originally published when Pratchett was just 17 years old. As the author struggled with memory loss, he went back to the story and re-edited it line by line. The new edition is being released in the U.S. this fall.

Pratchett spoke to NPR's Arun Rath about his long career, his approach to science-fiction and his memory.

Interview Highlights

On deciding to re-release The Carpet People

There's always going to be a difficulty here. An author writes a book, and that's the book at that point. And if the author writes the book again, then somehow something has gone wrong, if you see what I mean.

On the book's main characters

If they were too different from us, we can't sympathize with them in any way, I should imagine. It's very straight-forward. They're very small, they're in a carpet, and that's it. But they don't know they're in a carpet. To them it's like this great big forest.

On writing using dictation software

The style comes from the computer, in a sense. I give it the words, I watch them come down, and if they seem to me to be the right words there, I think I'm on a winner. It really isn't a problem. I'm a bit of a techy anyway, so talking to the computer is no big deal. Sooner or later, everybody talks to their computers — they say, "You bastard!"

On continuing to write as he loses his memory

Siren voices tell me, "You don't have to keep going on." And then you think, "I'm a writer. What do I do? Sit there watching my wife clean up?" I don't know. I like being a writer. The book I'm writing right now is gonna be a good one, I believe. If it gets really bad, get the little men to go into the flying saucer and take me away from it all.

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Transcript

ARUN RATH, HOST:

If you're just joining us, it's ALL THINGS CONSIDERED from NPR West. I'm Arun Rath.

Sir Terry Pratchett is one of Britain's bestselling authors, second only to J.K. Rowling. His science-fiction series "Discworld" has sold millions of copies worldwide. And Pratchett is incredibly prolific, publishing an average of two books a year. But in 2007, Terry Pratchett announced that he had been diagnosed with early-onset Alzheimer's. As a result, Pratchett can no longer read, yet he continues to write.

This week, Pratchett is publishing a reedited version of his first novel, "The Carpet People," which he wrote when he was just 17 years old. It's a book for young readers about a whole world of tiny people living deep in the hairs of a carpet. I sat down with Pratchett earlier this fall and asked him where he got the idea for "The Carpet People."

TERRY PRATCHETT: One day, I had a friend with me and we were just hanging out. And he was sort of walking around the room, and I said: Don't keep doing that. You'll upset the carpet people. Heaven knows why I said it. But a little bit later, I wondered whether it would be possible to do a fantasy of very, very small people who live in the very depths of the carpet.

(LAUGHTER)

RATH: And I want to talk about the story of the book. These main characters, they're these tiny people that live in the carpet. Let's hear an excerpt, the opening of the story.

UNIDENTIFIED MAN: (Reading) They called themselves the Munrungs, and it meant the people or the true human beings. It's what most people call themselves to begin with. Then one day, the tribe meets some other people, and it gives them a name like the other people, or if it's not been a good day, the enemy. If only they'd think up a name like some more true human beings, it'd save a lot of trouble later on.

RATH: These tiny people, they're not really very different from us, are they?

PRATCHETT: If they were too different from us, we can't sympathize with them in any way, I should imagine. It's very straightforward. They're very small. They're in a carpet, and that's it. But they don't know they're in a carpet. To them, it's like this great big forest. I was younger in those days.

RATH: Well, you wrote it when you were 17. And is it safe to say that as a writer, you're rather critical of that 17-year-old's work now?

PRATCHETT: Well, yes. But there's always going to be a difficulty here. An author writes a book, and that's the book at that point. And if the author writes the book again, then somehow, something has gone wrong, if you see what I mean. And, really, it was just a children's book. I had a great deal of fun writing it, and then more or less I forgot it.

RATH: There's something also about the story and about your writing is that while these are fantastic and kind of fantasy worlds, they don't resort to as much kind of magic or mysticism, if you know what I mean.

PRATCHETT: Well, if we're getting down and dirty, you can make magic very quickly just by changing one single thing in the world. If you change the speed of light, for example, things would be different. If you took the moon away, things would be different.

RATH: So there would still be natural laws, laws of physics, but everything would be changed.

PRATCHETT: Well, as the writer, you just decide what to change.

RATH: For American listeners who don't know, I want to talk a little bit about your memory because it's part of the story. People in the UK are probably more aware of how when you were only 59 years old you were diagnosed with Alzheimer's. And it's a peculiar form of the disease that affects your vision, especially.

PRATCHETT: Well, yes. In fact, what I have is called PCA. It's a kind of Alzheimer's. For example, I can't read a book. When you read, I'm sure you don't realize that your eyes are going backwards and forwards and to this place and that place. Mine don't do that.

RATH: How do you use technology to help you still create the way that you have been for the last several years?

PRATCHETT: Are you familiar with track and dictate?

RATH: Yes. This is automatic dictation software.

PRATCHETT: I tried using it. And I went onto the Web and said, this is pretty good, but I think it could be better. And a couple of guys here in England contacted me and said: We've designed something to make track and dictate better to use. It's called Talking Point. And I was using it only yesterday.

RATH: Do you feel like your voice has changed at all in the last several years?

PRATCHETT: Well, the style comes from the computer in a sense. I give it the words, I watch them come down, and if they seem to me to be the right words there, I think I'm on a winner. It really isn't a problem. I'm a bit of a techy anyway, so talking to the computer is no big deal. Sooner or later, everybody talks to their computers. They say: You, bastard!

(LAUGHTER)

RATH: So how long do you think you'll be able to keep on like this to keep writing?

PRATCHETT: Well, I think it's a race between what you might call the death that comes to everybody and to the PCA. If that catches me before that happens, then, well, I've gone, haven't I? Siren voices tell me, you don't have to keep going on. And then you think, well, I'm a writer. If I - what do I do? I like being a writer. The book I'm writing now is going to be a good one, I believe. If it gets really bad, we'll get the little men to go into the flying saucer and take me away from it all.

RATH: Well, I wonder if you're hinting at something you've spoken about before, which is the issue of assisted suicide, I know you've been very vocal about. Is that what you're getting at?

PRATCHETT: Yes.

RATH: Can I ask you - I understand that you've had the - you have the music picked out that you want to listen to when you take the final exit.

PRATCHETT: Yes. Thomas Tallis, "Spem in Alium."

RATH: And this is a glorious piece of vocal music, and I was wondering if you could talk about why you want that piece.

PRATCHETT: It's kind of a strange thing. My family had no religion. It still doesn't. My parents reckoned that Jesus was a decent man and ought to be listened to. But they didn't like the local clergyman. So I have no God. I'm quite happy about it, really.

RATH: But this piece of religious music speaks to you somehow?

PRATCHETT: Yes, because it's - well, music is eternal, one might say. That's "Spem in Alium." The first time I heard it, my wife was playing it in the kitchen. And actually, I fell down on my knees just because of the magic. I didn't know what it was about, but Thomas Tallis, good grief, what highly written.

(SOUNDBITE OF MUSIC, "SPEM IN ALIUM")

RATH: Terry Pratchett is the legendary science fiction writer. He spoke to us from London. Terry Pratchett, thank you so much.

PRATCHETT: Thank you very much.

(SOUNDBITE OF MUSIC, "SPEM IN ALIUM")

RATH: And for Sunday that's ALL THINGS CONSIDERED from NPR News. I'm Arun Rath. We're back next weekend. Until then, thanks for listening and have a great week. Transcript provided by NPR, Copyright NPR.